<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>边框</title>
    <style>
        div{
            width: 300px;
            height: 300px;
            /*border: 1px solid red;   复合样式*/
            /*单一样式*/
            border-width: 1px 2px 3px 4px;
            border-style: solid dashed dotted solid;
            border-color: red green blue black;
        }

        /*border-width: 1px 2px 3px 4px;
                        上   右  下   左*/
    </style>
</head>
<body>
    <div></div>
</body>
</html>